The incidence and outcome of single-factor, multifactorial, and unexplained infertility.

Infertility may have many etiologies. Of 141 systematically and completely evaluated couples, 40.4% were found to have multiple factors contributing to their inability to conceive. In 33.3% two factors were present, and in 7.1% three or more factors were found. A total of 53.2% of patients had a single identified factor, and in 6.4% no apparent cause was identified. Long-term pregnancy rates calculated by life-table methodology revealed no significant differences between those with single-factor, multifactorial, or unexplained infertility when all identified factors were treated.